I take it that the detection is on the reflexive.com site and is blocked by the Web Shield, the only option is Abort connection ?
If so even sites that you think safe can get hacked.
I have visited reflexive.com and not got an alert so you are going to have to give more information on the detection.
What is the infected file name, where was it found e.g. (C:\windows\system32\infected-file-name.xxx) ?
Check the avast! Log Viewer (right click the avast 'a' icon), Warning section, this contains information on all avast detections.
I'm on dial-up so I can try to download anything large game files, not that it appears easy to do that without signing up.
You could also check the offending/suspect file (you may need to pause the web shield to download it, just don't try to execute it) at:
VirusTotal - Multi engine on-line virus scanner and
report the findings here. You can't do this with the file securely in the chest, you need to extract it to a temporary (not original) location first, see below.
Create a folder called Suspect in the C:\ drive, e.g. C:\Suspect. Now exclude that folder in the
Standard Shield, Customize, Advanced, Add, type (or copy and paste) C:\Suspect\* That will stop the standard shield scanning any file you put in that folder. You should now be able to export any file in the chest to this folder and upload it to VirusTotal without avast alerting.
If it is indeed a false positive, see
http://forum.avast.com/index.php?topic=34950.msg293451#msg293451, how to report it to avast! and what to do to exclude them until the problem is corrected.